JSTARS - Joint Surveillance and Target Attack Radar System, United States of America

The joint surveillance and target attack radar system (JSTARS) is a joint development project of the US Air Force and Army which provides an airborne, stand-off range, surveillance and target acquisition radar and command and control centre.

In September 1996, JSTARS was approved for full-rate production for 14 aircraft, the last of which was delivered in August 2002. Three further aircraft were delivered between February 2003 and March 2005. The 116th Air Control Wing operates the JSTARS aircraft at Robins Air Force Base in Georgia. The 116th is a 'blended wing' with both air force and air national guard personnel.

Joint STARS Surveillance and Target Attack Radar System programme

JSTARS provides ground situation information through communication via secure data links with air force command posts, army mobile ground stations and centres of military analysis far from the point of conflict. JSTARS provides a picture of the ground situation equivalent to that of the air situation provided by AWACS. JSTARS is capable of determining the direction, speed and patterns of military activity of ground vehicles and helicopters.

JSTARS was first deployed in Operation Desert Storm in 1991 when still in development, and has since been deployed to support peacekeeping operations in Bosnia-Herzegovina and during the Kosovo crisis.

"JSTARS provides an airborne, stand-off range, surveillance and target acquisition radar and command and control centre."

Eight JSTARS aircraft flew more than 50 missions in support of Operation Iraqi Freedom in March / April 2003.

On a standard mission the aircraft has a crew of 21 with three flight crew and 19 systems operators. On a long endurance mission the aircraft has a crew of 34, with six flight crew and 28 system operators.

JSTARS E-8C aircraft

The Boeing 707-300 series aircraft is the JSTARS airframe. The aircraft are remanufactured at Northrop Grumman in Lake Charles, Louisiana, then transferred to the Battle Management Systems Division in Melbourne, Florida where the electronics are installed and tested.

The propulsion system of the JSTARS aircraft consists of four Pratt & Whitney JT3D-3B turbojet engines, each providing 18,000lb of thrust. The aircraft has a flight endurance of 11 hours or 20 hours with in-flight refuelling.

In March 2007, Northrop Grumman was awarded a contract for the re-engining of the JSTARS fleet. The Pratt & Whitney / Seven Q Seven team was selected in January 2007 to provide the new integrated propulsion pod system including the P&W JT8D-219 engine. Northrop Grumman began work on the first testbed aircraft in May 2008 and the first flight of the E-8C JSTARS with the new engines took place in December 2008. The first retrofitted aircraft will be delivered in late 2010 and the programme is expected to complete in 2013.

JSTARS airborne radar system

The radar system is produced by Northrop Grumman Norden Systems. A 24ft antenna is installed on the underside of the aircraft, which is mechanically swivelled and pointed to scan in elevation, and scans electronically in azimuth to determine the location and heading of moving targets.

"The main operating modes of the radar include wide area surveillance, fixed target indication, synthetic aperture radar."

The US Air Force has awarded Northrop Grumman a contract to develop the next generation JSTARS as part of the radar technology insertion programme (RTIP). The new much more powerful radar will be an electronically scanned 2D X-band active aperture radar which will have a helicopter detection mode and inverse synthetic aperture (ISAR) imaging capability, as well as MTI (moving target indicator) mode, allowing real-time imaging of moving objects.

Signal processing techniques are implemented through four high-speed data processors, each capable of performing more than 600 million operations a second. Processed information is distributed via high-speed computer circuitry to tactical operators throughout the aircraft.

In 1997, the US Air Force awarded Northrop Grumman two contracts for a computer replacement program to take advantage of the latest commercial off-the-shelf technology (COTS). The program integrates new Compaq AlphaServer GS-320 central computers that are significantly faster than the original system.

The programmable signal processors have been replaced and a high-capacity switch and fibre-optic cable replaces the copper-wired workstation network. The first upgraded aircraft under the computer replacement plan (CRP) was delivered in February 2002 and the programme was completed in August 2005.

JSTARS aircraft are being fitted with Force XXI Battle Command, Brigade and Below (FBCB2) 'Blue Force' tracking, which significantly improves the ability to locate and track the movement of friendly ground forces.

Communications

JSTARS has secure voice and datalinks to the army's ground command and communications stations and to the air force command centres. Voice communications systems include 12 encrypted UHF radios, two encrypted HF radios, three VHF encrypted radios with provision for single channel ground and airborne radio system (SINCGARS) and multiple intercom nets.

"JSTARS aircraft are being fitted with FBCB2 'Blue Force' tracking."

The digital datalinks include a satellite communications link (SATCOM), a surveillance and control datalink (SCDL) for transmission to mobile ground stations, and Joint Tactical Information Distribution System (JTIDS). The JTIDS provides tactical air navigation (TACAN) operation and Tactical Data Information Link-J (TADIL-J) generation and processing.

The Cubic Defense Systems SCDL is a time division multiple access datalink incorporating flexible frequency management. The system employs wideband frequency hopping, coding and data diversity to achieve robustness against hostile jamming. Uplink transmissions use a modulation technique to determine the path delay between the ground system module and the E-8 aircraft.